ASE A7 Test Prep (HVAC)

True

When the defrost setting is selected, the compressor operates.

(True or False)

True

R744 refrigerant is pure CO2

(True or False)

Both Technician A & B

Technician A says on R134a systems, you may not find any evidence of oil, even with a leak, because the lubricant is water soluble, and could wash away.

Technician B says never use compressed air to leak test or pressure test an R134a system.

Which technician is correct ?

Both Technician A & B

Technician A says when checking for a leak using an Electronic Leak Detector, you check from the bottom to the top of the AC component area.

Technician B says most OEMS (original equipment manufacturers) recommend using an Electronic Leak Detector.

Which technician is correct ?

Both Technician A & B

Technician A says you can find the refrigerant charge amount on a decal under the hood.

Technician B says the best way to make sure the air-conditioning system is properly charged is to remove all refrigerant from the system and reinstall the proper amount of refrigerant.

Which technician is correct ?

Technician B only

An Automatic Temperature Control system that uses a BCM (Body Control Module) is being diagnosed on a 2008 vehicle using a scan tool.

Technician A says you need a laptop computer with software to diagnose any of these systems.

Technician B says you connect the scan tool, turn on the ignition and use the menus to find your system and tests.

Which technician is correct ?

Both Technician A & B

An ATC (Automatic Temperature Control) system is being diagnosed for a high air outlet temperature.

Technician A says it is possible for a malfunctioning ATC control system to prevent correct operation even when the refrigerant system is operating to specs.

Technician B says you should use a diagnostic scan tool or laptop computer to identify ATC problems.

Which technician is correct ?

Air gap

Which of the following is the most important measurement done when replacing a compressor clutch?

a. Coil voltage drop
b. Coil Current (ampere) draw
c. Air gap
d. Coil resistance

Broken compressor reed valve

All of the following could cause the high side pressure in an AC system to be higher than normal, EXCEPT:

a. Refrigerant overcharge
b. Restricted condenser air flow
c. Restricted evaporator air flow
d. Broken compressor reed valve

Technician A only

Technician A says the pressure sensor disengages the compressor when low pressure is sensed because low refrigerant flow could result in a lack of lubrication and seize the compressor.

Technician B says air conditioning systems using a multi-pressure switch will display a data line for system pressure on the scan tool DATA parameter list.

Which technician is correct ?

ND-11

Which of the following refrigerant oil is recommended for use in a hybrid electric compressor?

a. ND-10
b. ND-11
c. ND-9
d. ND-8

Technician A only

On a manual air conditioning system without automatic control, the compressor clutch does not operate.

Technician A says there is a failed compressor thermal protector.

Technician B says there is an incorrectly adjusted temperature door.

Which technician is correct ?

Clutch air gap

All of the following could cause compressor drive belt edge wear, EXCEPT:

a. Clutch air gap
b. Bent mounting bracket
c. Damaged pulley
d. Worn pulley bearing

Sound can be heard when a compressor pulley engages and disengages.

All of the following statements related to compressors with damper limiter pulleys are correct, EXCEPT:

a. The pulley is attached to the compressor shaft by spokes that break if the compressor locks.
b. Sound can be heard when a compressor pulley engages and disengages.
c. If the pulley breaks, the compressor and the pulley are replaced as a unit.
d. If the pulley breaks, the pulley freewheels on the compressor shaft.

Reuse same compressor oil

All of the following tasks are performed when replacing an AC compressor, EXCEPT:

a. Reuse all mounting brackets
b. Use new gaskets and seals
c. Use the same or equivalent compressor
d. Reuse same compressor oil

Sealant is used to repair minor leaks.

All of the following statements are correct regarding AC system service, EXCEPT:

a. Use a Refrigerant Identifier
b. The service technician must be AC certified.
c. Contaminated refrigerants are NEVER released to the atmosphere.
d. Sealant is used to repair minor leaks.

Internal compressor damage

All of the following issues are present with a cracked AC compressor mounting plate, EXCEPT:

a. Drive belt wear
b. Internal compressor damage
c. Compressor vibration
d. Drive belt squeal

Incorrect air gap

A compressor clutch will not engage. Power and ground at the clutch coil are good.
Which of the following is the MOST likely cause?

a. Low refrigerant
b. Locked-up compressor
c. Incorrect air gap
d. Bad pressure cycling switch

Neither Technician A nor B

Technician A says with a properly operating orifice-tube controlled AC system, the compressor inlet is hot to the touch and the outlet is cold to the touch.

Technician B says the inlet to the evaporator is hot and the accumulator inlet is cold.

Which technician is correct ?

Both Technician A & B

Technician A says many O rings and gaskets are specific to R12 and R134a systems because they are made from different material.

Technician B says never reuse an O ring or gasket regardless of its appearance.

Which technician is correct ?

Both Technician A & B

Technician A says if both the high-side and low-side gauge pressures are high, the condenser air flow is restricted.

Technician B says a worn, glazed or cracked belt can slip, reducing system efficiency, and can cause noises that can be mistaken for a compressor noise.

Which technician is correct ?

Low refrigerant level

The AC system has an outside temperature of 85° F and the low -side pressure gauge shows 5 psi with the high-side pressure gauge reading of 105 psi.
These readings indicate which of the following?

a. High-side restriction
b. Low refrigerant level
c. Low-side restriction
d. Defective compressor

Evacuating system removes moisture from a saturated receiver/dryer

All of the following issues regarding a receiver/dryer are correct, EXCEPT:

a. Clogged filter can cause higher than normal pressure
b. Saturated desiccant can cause a blockage due to freezing
c. You install a new desiccant bag on some systems before charging the system.
d. Evacuating system removes moisture from a saturated receiver/dryer

Technician A only

Water is found dripping under the passenger's side of the vehicle.

Technician A says this is a normal condition due to condensation on the evaporator.

Technician B says the evaporator housing is defective and needs to be replaced.

Which technician is correct ?

Stuck expansion valve

A concern of intermittent AC cooling is being diagnosed. The gauge set shows intermittently high and low side pressure gauge readings and the high side intermittently drops to 100 psi.
Which of the following is the MOST likely cause?

a. Stuck expansion valve
b. Overcharged A/C System
c. Compressor internal leak
d. Damaged compressor reed valve

Technician B only

Technician A says you can replace a Schrader type valve core on the low side fitting with one from a vehicle tire Schrader valve.

Technician B says R134a refrigerant containers must be EPA approved and are a safety item.

Which technician is correct ?

Defective Compressor

An air conditioning system does not cool with the high and low side lines warm to the touch. The low-side pressure is higher than normal with the high-side pressure is lower than normal with the high side gauge needle vibrating.
Which of these is the MOST likely cause?

a. Stuck closed Expansion Valve
b. Defective Compressor
c. Overcharged A/C System
d. Undercharged A/C System

Technician B only

Technician A says all air conditioning connections use compression fittings to seal the system.

Technician B says when replacing O-rings you lubricate the O-ring with the correct refrigerant oil to prevent nicks and ease installation.

Which technician is correct ?

Thermal expansion valve (TXV)

While recovering refrigerant, the high-side gauge follows the low-side gauge very quickly with no pressure rise.
This test confirms that there is problem in which of the following?

a. Condenser
b. Suction throttling valve (STV)
c. Receiver/dryer
d. Thermal expansion valve (TXV)

Quick-disconnect valves

What type of service valves are used with R-134a?

a. Schrader valves
b. Gate valves
c. Quick-disconnect valves
d. Saddle valves

When stuck closed, pressure on high side is low and pressure on low side is high.

All of the following are true regarding the expansion valve, EXCEPT:

a. When stuck closed, pressure on high side is low and pressure on low side is high.
b. It can fail in the open position as a result of debris in the system.
c. It can seize in the closed position due to a lack of lubricant.
d. With moisture in the system, ice can form and cause blockage.

Technician B only

Technician A says it is alright to replace a vehicles thermostat with one that opens at a lower temperature. Technician B says you can use a scan tool or laptop computer to identify most ATC (automatic temperature control) problems.

Which technician is correct ?

Sight-glass diagnosis

All of the following diagnostic methods are used for many Automatic Air Conditioner systems, EXCEPT:

a. Touch and Feel
b. Self-Diagnosis process
c. Scan tool
d. Sight-glass diagnosis

Excessive refrigerant charge

Both high and low-pressure sides are too high. The pressure is reduced after water is splashed on the condenser.
Which of the following could be the cause?

a. Stuck open TXV (Thermal expansion valve)
b. Stuck closed TXV (Thermal expansion valve)
c. Excessive refrigerant charge
d. Insufficient refrigerant charge

Both Technician A & B

Technician A says a radiator should always be inspected for leaks before installing a rebuilt engine.

Technician B says overheating during slow in-town driving can be caused by an electric cooling fan fault.

Which technician is correct ?

Check the air mix door linkage

On a vehicle equipped with a manual temperature control system the discharge air temperature does not change.
After checking for service bulletins, which of the following is the next step?

a. Check the LAN System circuit
b. Check the air mix door linkage
c. Check the mode door linkage
d. Check the in-car sensor circuit

500 microns

Which of the following readings represents a very low vacuum or absence of pressure reading?

a. 15 inches Hg
b. 5,000 microns
c. 27 inches Hg
d. 500 microns

Check for technical service bulletins

A technician is checking the blower motor operation on a manual AC system with the engine running and at normal operating temperature. The blower motor speed does not increase above low.
Which of the following actions should the technician take first?

a. Check blower motor circuit
b. Check for technical service bulletins
c. Replace high blower relay
d. Adjust the temperature door

Disconnected engine vacuum line

An AC system only blows cold air out of the bottom heater ducts.
Which of the following could be the cause?

a. Defective evaporator case
b. Defective heater core case
c. Disconnected engine vacuum line
d. Defective thermostat

Ground

When using the voltmeter function of a Digital Multimeter (DMM), the black lead is connected to which of the following?

a. Positive side of circuit
b. Non-conductive surface of battery
c. Ground
d. At any location

Technician A only

Technician A says you can test the intake door position by placing a piece of paper over the intake vent on the cowl.

Technician B says the paper will be blown away from the cowl when the system is in the "fresh" position.

Which technician is correct ?

Technician A only

Technician A says operational checks found in the on-line service information are used to verify which AC functions are working.

Technician B says a restricted airflow in a condenser cause low high-side and low-side pressures.

Which technician is correct ?

Both Technician A & B

Technician A says that after a compressor failure it is a good idea to add an additional filter designed to catch a small amount of debris that may still be in the system from the compressor failure.

Technician B says that additional filters are generally placed in the liquid line after the condenser, but before the restriction.

Which technician is correct ?

Solar or sun load sensor

A vehicle with an automatic air conditioning and heating system has a customer concern of reduced blower speed.

Which of the following is the MOST likely cause?

a. Recirculation door
b. Heater door
c. Solar or sun load sensor
d. Ambient sensor

Duct air leaks

During the operation check of a manual AC control system, the temperature does not increase.
All of the following could cause this condition, EXCEPT:

a. Thermostat stuck open
b. Engine coolant level low
c. Mix door operation
d. Duct air leaks

Technician B only

Technician A says dual zone systems separate the zones after the air passes through the heater core.

Technician B says dual zone systems have only one evaporator and one heater core.

Which technician is correct ?

Technician A only

Technician A says a misadjusted temperature door could cause a poor heat complaint.

Technician B says a defective resistor trio can cause a no high blower condition.

Which technician is correct ?

Technician A only

A technician is using the owner's manual to check the manual control system operation.

Technician A says for quick heating the air recirculation button should be in the "on" position.

Technician B says the AC should never be "on" when the temperature control is in the "hot" position.

Which technician is correct ?

Defective thermostat

A customer complains about constant heat out of the air ducts with normal air conditioning pressures and operation.
All of the following could be the cause, EXCEPT:

a. Blend door adjustment
b. Defective heater control valve
c. Defective thermostat
d. Heater control cable adjustment

Technician A only

A manual AC system is being checked for proper operation.

Technician A says when selecting the DEF (defrost position), the AC compressor should be on.

Technician B says that recirculation air will also operate in the DEF.

Which technician is correct ?

Technician B only

The heater blows out only cold air at operating temperature.

Technician A says a stuck closed thermostat could be the cause.

Technician B says the cooling system could be low on coolant.

Which technician is correct ?

Technician A only

The engine cooling fan does not operate properly on a late model vehicle but works okay when the engine is hot in city driving.

Technician A says there could be a problem with the engine computer.

Technician B says there could be a problem with the engine temperature sensor.

Which technician is correct ?

Check the coolant level in overflow bottle and radiator.

Which of the following is the first step in bleeding a cooling system?

a. Run the engine between idle and 4,000 RPM.
b. Start the engine and bring it to operating temperature.
c. Check the coolant level in overflow bottle and radiator.
d. Look for air bubbles in the reservoir and listen for air.

The air is not cool enough.

Which of the following would happen if the air mix door motor is improperly positioned on an Automatic Air Conditioner system with an adjustable air mix door motor?

a. The air is not cool enough.
b. Air comes out the wrong vents.
c. Defrost does not work.
d. Air is stuffy.

Infrared Thermometer

Which of the following tools should be used to check the engine cooling system thermostat opening and operating temperature?

a. Manometer
b. Infrared Thermometer
c. Digital Multimeter
d. Digital Storage Oscilloscope

Technician A only

Technician A says the lower radiator hose contains a spring to prevent it from collapsing and causing a restriction.

Technician B says you replace the engine cooling thermostat once a year.

Which technician is correct ?

Technician A only

Technician A says the cooling system should be tested for leaks using a hand operated pressure tester.

Technician B says the freezing temperature of the coolant can be tested using a thermometer.

Which technician is correct ?

Technician A only

Technician A says poor airflow through the heater core could cause a low heat complaint.

Technician B says a high coolant level could cause a poor heat complaint.

Which technician is correct ?

Both Technician A & B

Technician A says a defective thermostat can cause the engine to operate at too cold of a temperature.

Technician B says if the thermostat is stuck closed it can make a pinging or banging sound.

Which technician is correct ?

Technician B only

Two technicians are describing heater diagnosis.

Technician A says if one heater hose is hot to the touch and the other hose is cold, then the heater core is functioning okay.

Technician B says the upper radiator hose should be at engine operating temperature, which is very hot to the touch.

Which technician is correct ?

Technician B only

Technician A says anytime silicone fluid is leaking out of the radiator fan viscous clutch, the fan clutch must be replaced.

Technician B says you should inspect all types of fan blades for stress fractures.

Which technician is correct ?

Type and mixture as required in the service information

After flushing the engine coolant, you refill the system with which of the following coolant mixtures?

a. 50% ethylene glycol and 50% propylene glycol
b. 75% antifreeze and 25% water
c. Type and mixture as required in the service information
d. 50% water and 50% antifreeze

Collapsed upper radiator hose after engine shut-down

When the vacuum valve in a radiator cap is stuck closed, which of the following could happen?

a. High cooling system pressure at normal engine temperature
b. Collapsed upper radiator hose after engine shut-down
c. Engine overheating under heavy load
d. Engine overheating during idle

Technician B only

Technician A says you can replace the engine thermostat with one that opens at a lower temperature.

Technician B says exhaust emissions affect what thermostat is installed in a cooling system.

Which technician is correct ?

Technician B only

Technician A says removing the thermostat from the coolant system will repair an overheating concern.

Technician B says poor airflow through the heater core could cause a blower motor resistor to burn out.

Which technician is correct ?

Clogged radiator

Which of the following conditions is the MOST likely cause of a vehicle overheating?

a. Electric cooling fan runs all the time
b. Restricted heater core
c. Thermostat stuck open
d. Clogged radiator

Both high and low-side are high

What high-side and low-side pressure gauge readings would a technician find if the condenser fan were inoperative?

a. High-side high and low-side low
b. High-side low and low-side high
c. Both high and low-side are low
d. Both high and low-side are high

Technician A only

An engine overheats within the first ten (10) minutes of operation.

Technician A says the thermostat is sticking.

Technician B says the water pump is slipping.

Which technician is correct ?

Both Technician A & B

The automatic air conditioning system blows hot air.

Technician A says you can use the scan tool or laptop computer snap shot mode to monitor system parameters during a test drive.

Technician B says using a digital multimeter (DMM) for diagnosis may not capture intermittent faults.

Which technician is correct ?

Engine running at 3,500 rpm

All of the following are steps to an AC performance test, EXCEPT:

a. Air conditioning set to ON and blower speed be set to HIGH
b. Engine running at 3,500 rpm
c. Temperature set to maximum cool with all doors open
d. Mode control set to recirculation

To avoid outside odor, operate AC System in Normal rather than Recirc mode.

All of the following statements are correct regarding an air conditioning performance test, EXCEPT:

a. Road debris can clog the condenser fins reducing system performance.
b. To avoid outside odor, operate AC System in Normal rather than Recirc mode.
c. Passenger-side floor being wet is one symptom of a clogged evaporator drain line.
d. Obstructions of the cabin air filter may cause insufficient air circulation.

Both Technician A & B

Technician A says a service technician must wear safety glasses whenever the ACR-4 (recover, recycle, remove and recharge) is connected to the AC system.

Technician B says it is against the US Clean Air Act and Montreal Protocol to release R-134a to the atmosphere and is, therefore, a crime.

Which technician is correct ?

Technician A only

Technician A says pressure gauges on an R134a system are connected to 2 different service ports, colored blue for the low-pressure side and colored red for the high-pressure side.

Technician B says you test for R134a pressure with the engine off.

Which technician is correct ?

Neither Technician A nor B

Technician A says you can use R12 and R134a with the same equipment using a separate set of charging hoses.

Technician B says R12 and R134a systems use the same refrigerant oil in the compressor.

Which technician is correct ?

Technician A only

Technician A says according to EPA Regulations you must have shut-off valves where the R134a service hoses connect to the manifold within 12 inches of service hose ends.

Technician B says when charging an R134a system with a sight glass in the receiver/dryer, you add refrigerant until the sight glass is clear.

Which technician is correct ?

Technician B only

Technician A says SAE (Society of Automotive Engineers) 5 weight engine oil should be used in R12 systems.

Technician B says PAG (Polyalkylene Glycol) or synthetic oil is usually the oil specified by OEMS (original equipment manufacturers) for use in HFC-134a systems.

Which technician is correct ?

Technician A only

During an air conditioning performance test, the technician notices that the compressor outlet is hot.

Technician A says this is a normal condition.

Technician B says the air conditioning system is overcharged.

Which technician is correct ?

Neither Technician A nor B

An R12 system is being upgraded to R134a.

Technician A says hoses replaced on R12 systems must use barrier type hoses.

Technician B says non-barrier type hoses use barbed type fittings.

Which technician is correct ?

Technician A only

Technician A says R12 and R134a may be recycled in your shop; most other refrigerants must be recovered and sent to a waste disposal facility.

Technician B says all refrigerants do not need to be recovered.

Which technician is correct ?

High on both high and low pressure gauges

When the condenser airflow is restricted the pressure is which of the following?

a. High side pressure low and low side pressure is low
b. Low side pressure low and high side pressure is high
c. High on both high and low pressure gauges
d. Low side pressure high and high side pressure is low

High-side readings 199-228 psi; Low-side readings 21-36 psi

Normal AC pressure gauge readings on a day with an outside temperature of 90° F should fall within which of the following?

a. High-side and low-side readings about the same 50-100 psi
b. High-side and low-side readings about the same 100-200 psi
c. High-side readings 100-250 psi; Low-side reading 35-40 psi.
d. High-side readings 199-228 psi; Low-side readings 21-36 psi

Recovery

What process listed below removes all R12 or R134a refrigerant from a system and then stores it in an external EPA approved tank?

a. Recovery
b. Recycling
c. Reclaiming
d. Removal

Compressor

A technician is checking for a properly operating AC system using an infrared thermometer.
The outlet should be hot from which of the following A/C components?

a. Expansion valve
b. Accumulator
c. Compressor
d. Orifice tube

Technician A only

Technician A says evacuating an AC system removes air and moisture from the system.

Technician B says evacuating an AC system removes dirt particles from the system.

Which technician is correct ?

Technician A only

Technician A says the CANDi (Controller Area Network Device Interface) module used on GM vehicles will flash an LED rapidly if communication is detected.

Technician B says late model OBD II (on board diagnostic generation II) vehicles use a jumper wire to connect two pins of the Data Link Connector to read Diagnostic Trouble Code on a scan tool.

Which technician is correct ?

30 minutes, 5 minutes

Which of the following is the smallest amount of time a system is evacuated and the minimum time to hold that vacuum?

a. 20 minutes, 10 minutes
b. 15 minutes, 5 minutes
c. 30 minutes, 5 minutes
d. 10 minutes, 10 minutes

Remove the trapped refrigerant

After waiting the required time for the Recycling/Recovery/Recharging machine to finish, you discover 5 psi in the system.
Which of these actions should you follow?

a. No action, this is a normal
b. The machine is defective call for service.
c. There is a leak in the system and air has entered the system.
d. Remove the trapped refrigerant

DLC (Data Link Connector)

To which of the following devices does a technician connect a scan tool or laptop computer to diagnose an AC system?

a. BCM (Body Control Module)
b. STAICE (Simplified Test Approach Internal Combustion Engine)
c. DLC (Data Link Connector)
d. PCM (Power Train Control Module)

Recover into a disposable tank

During engine removal and prior to recovering the refrigerant, an unknown refrigerant is found using a refrigerant identifier.
What should be done with the refrigerant?

a. Discharge into the atmosphere
b. Recover into a disposable tank
c. Recover and recycle as R-12
d. Recover and recycle as R-134a

Technician B only

Two technicians are explaining refrigerant recycling.

Technician A says refrigerants are checked for condensable gases such as air.

Technician B says a shop must have certified technicians doing AC service.

Which technician is correct ?

Recover and recharge the system

A technician is going to charge an AC system with R134a. Which of the following is the MOST accurate way to know the amount of refrigerant in the system?

a. Recover and recharge the system
b. Low side pressure stays at 50 PSI for R12 and 75 for R134a
c. Recover the refrigerant into an EPA approved tank and weigh it
d. High side pressure stays at 100 PSI for R12 and 125 for R134a

Before any service

When should R134a refrigerant be checked for contamination?

a. Before any service
b. After recycling
c. Before charging
d. After charging

Disconnect battery negative cable

Which of the following is the first and most important step when disabling the air bag to service an AC system?

a. Disconnect battery negative cable
b. Disconnect clock-spring electrical connector
c. Check resistance at the clock spring connector
d. Disconnect the seat position sensors

Red

The refrigerant identifier filter in the ACR4 machine must be visually checked every day. If the liquid refrigerant gets in the sample line, the filter is defective and will bleed what color dye?

a. Black
b. Gray
c. Red
d. Cloudy

Air

Which of the following is a non-condensable gas?

a. Air
b. R-12
c. Atmospheric Ozone
d. R-134a

A. To avoid evaporator odor, you want to operate the AC in RECIRC instead of FRESH

All of these statements regarding an air conditioning performance test are true EXCEPT:

A. To avoid evaporator odor, you want to operate the AC in RECIRC instead of FRESH

B. Obstructions of the cabin filter might create insufficient air circulation

C. Road debris might clog the condenser fins which lead to a decrease in performance

D. If the passenger side floor is wet, it could be a clogged evaporator drain line.

475 psi (3,275 kPa)

The A/C compressor high-pressure release valve discharges refrigerant at what approximate measurement?

A. 200 psi (1,379 kPa)

B. 325 psi (2,240 kPa)

C. 375 psi (2,585 kPa)

D. 475 psi (3,275 kPa)

Both Technician A & B

Technician A states that when the condenser airflow is restricted, the pressure is high in both the high and low lines.

Technician B states that when both high and low sides show low pressure, it's often an indication of low refrigerant.

Which technician is correct ?

D. You must discharge the refrigeration system before the A/C control panel removal.

All of these statements regarding A/C-heater control panel service are accurate EXCEPT:

A. In an air-bag equipped vehicle, you must wait the specified period once the negative battery cable is disconnected.

B. The negative battery cable needs to be disconnected before A/C control panel removal.

C. Self-diagnostic tests might indicate a defective A/C control panel in the computer-controlled system.

D. You must discharge the refrigeration system before the A/C control panel removal.

C. Air blend door is stuck.

Incoming air is heated in the vent position with the temperature selector in the cool position. What might be the problem?

A. Heater core is clogged.

B. Cooling fan is inoperative.

C. Air blend door is stuck.

D. Low coolant in the radiator.